Properties of Matter 4 Question 5
7. A glass tube of uniform internal radius $(r)$ has a valve separating the two identical ends. Initially, the valve is in a tightly closed position. End 1 has a hemispherial soap bubble of radius $r$. End 2 has sub-hemispherical soap bubble as shown in figure. Just after opening the valve.
(2008, 3M)
(a) air from end 1 flows towards end 2. No change in the volume of the soap bubbles
(b) air from end 1 flows towards end 2. Volume of the soap bubble at end 1 decreases
(c) no change occurs
(d) air from end 2 flows towards end 1. Volume of the soap bubble at end 1 increases
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Answer:
Correct Answer: 7. (b)
Solution:
- $\Delta p _1=\frac{4 T}{r _1}$ and $\Delta p _2=\frac{4 T}{r _2}$
$$ r _1<r _2 \Rightarrow \Delta p _1>\Delta p _2 $$
$\therefore$ Air will flow from 1 to 2 and volume of bubble at end 1 will decrease.
Therefore, correct option is (b).
